Cerebral palsy (CP) is a group of neurological disorders caused by damage to the developing brain, affecting a person’s ability to control their muscles. It occurs in roughly 2 to 3 out of every 1,000 live births, making it the most common motor disability in childhood. The brain injury that causes CP is non-progressive, meaning it doesn’t get worse over time, but its effects on movement, posture, and coordination are lifelong.
What Happens in the Brain
Cerebral palsy results from abnormal brain development or injury to the brain before, during, or shortly after birth. The damage typically affects the motor cortex and the nerve pathways that carry movement signals from the brain to the body. When these pathways are disrupted, the brain struggles to coordinate muscles properly.
The effects go beyond a single brain area. Children with CP show reduced connectivity between several regions involved in motor control: the areas responsible for planning movements, executing them, and integrating sensory feedback. In children where both sides of the brain are affected, the disruption is widespread. When only one hemisphere is damaged, the motor difficulties tend to show up primarily on the opposite side of the body.
Types of Cerebral Palsy
CP looks different depending on which type of movement is affected and which parts of the body are involved.
Spastic cerebral palsy is the most common form. It causes stiff, tight muscles that produce jerky or repeated movements. Spastic CP is further divided by the body parts affected:
- Hemiplegia: affects one side of the body, typically the arm and hand more than the leg. Children with this form may have some speech delays but usually have normal intelligence.
- Diplegia: mainly affects the legs, with the arms and face less involved. Intelligence and language skills are usually unaffected.
- Quadriplegia: the most severe form, involving stiffness in all four limbs and a weak, floppy neck. Walking and speaking are often significantly limited, and moderate to severe intellectual disability is common.
Dyskinetic cerebral palsy causes slow, uncontrollable movements of the hands, feet, arms, or legs. The muscles of the face and tongue can also be overactive, sometimes causing drooling or involuntary facial expressions. Sitting upright and walking are often difficult, but intellectual ability is typically not affected.
Ataxic cerebral palsy affects balance and depth perception. People with this form walk unsteadily and have difficulty with quick or precise movements like writing, buttoning a shirt, or reaching for objects.
Mixed types involve symptoms from more than one category.
Causes and Risk Factors
Most cases of CP originate before or during birth. The major risk factors include:
- Premature birth: babies born before 37 weeks, and especially before 32 weeks, face a significantly higher risk.
- Low birth weight: babies weighing less than 5 pounds 8 ounces are at greater risk, and the risk increases further for those under 3 pounds 5 ounces.
- Infections during pregnancy: certain infections in the mother, including rubella, chickenpox, cytomegalovirus, and bacterial infections of the placenta or fetal membranes, can trigger inflammation that damages the developing brain.
- Birth complications: placental detachment, uterine rupture, or umbilical cord problems can cut off oxygen to the baby.
A smaller number of cases develop after birth, from events like severe infections or head injuries during infancy. In many cases, no single cause is identified.
Early Signs and Diagnosis
CP typically becomes noticeable between 6 and 9 months of age, when babies begin reaching for objects and trying to move their limbs with purpose. Parents and doctors may notice a child preferring one hand much earlier than is typical, asymmetric movements, or delays in hitting motor milestones. Key milestones that raise concern include head control by 2 months, rolling by 4 months, sitting by 6 months, and walking by 12 months.
Before a formal diagnosis, observation alone can reveal telling signs: unusual stiffness or floppiness in the neck and trunk, asymmetric posture, or uncoordinated movement patterns. Diagnosis involves a thorough neurological examination, brain imaging (usually an MRI), and clinical judgment. One widely used assessment tool, the Hammersmith Infant Neurological Examination, evaluates cranial nerve function, posture, movements, muscle tone, and reflexes in infants between 2 and 24 months. A skilled clinician can complete it in 10 to 15 minutes, and it provides a standardized score that helps predict whether a child has CP.
Severity Levels
Doctors classify the physical impact of CP using the Gross Motor Function Classification System (GMFCS), a five-level scale based on what a child can currently do rather than what’s wrong with them. At Level I, children can walk without restrictions but may have trouble with advanced motor skills like running or jumping. Levels II and III describe children who walk with increasing difficulty or need assistive devices. At Level IV, children use wheelchairs for most mobility. At Level V, children have very limited ability to move themselves even with assistive technology, and the likelihood of independent walking is extremely low.
The GMFCS level is one of the strongest predictors of what daily life will look like for a child with CP, influencing everything from school participation to the types of therapy that will be most helpful.
Conditions That Often Accompany CP
CP rarely affects movement alone. In one clinical study, nearly half of children with CP (47.7%) had some degree of intellectual disability, and 41.6% had epilepsy. Speech delays were present in about 28% of cases, while hearing and vision problems each affected roughly 10%. These co-occurring conditions often shape a child’s needs as much as the motor difficulties themselves, and they’re a major reason why CP care involves a team of specialists rather than a single doctor.
Treatment and Therapies
There is no cure for CP, but a combination of therapies can significantly improve function and quality of life. Physical therapy is the cornerstone, helping children build strength, improve balance, and develop the motor skills they need for daily activities. Occupational therapy focuses on fine motor tasks like eating, dressing, and writing. Speech therapy addresses both communication difficulties and swallowing problems.
For children with spastic CP, managing muscle stiffness is a central goal. Medications delivered through an implanted pump can reduce spasticity throughout the body. A surgical procedure called selective dorsal rhizotomy, which involves cutting specific nerve fibers in the spinal cord, can permanently reduce leg stiffness and improve walking ability. In some children who’ve been on pump-delivered medication for years, switching to this surgery has led to meaningful improvements in mobility.
Braces, walkers, and wheelchairs help children move as independently as possible. As children grow, their needs change, and treatment plans are adjusted regularly.
Life Expectancy and Adulthood
Virtually all children diagnosed with CP survive into adulthood. For those without severe impairments, survival rates are close to those of the general population: 99% of children with CP and no severe disability reach age 30. Even among children with severe CP, survival has been steadily improving at a rate of about 3.4% per year.
The number and severity of additional disabilities have the biggest impact on long-term survival. Children with one severe disability (such as inability to walk) have a 95% chance of reaching adulthood. That drops to 78% with two severe disabilities, 59% with three, and 33% with four. Among adults with CP who were alive at age 20, 86% survived to age 50 in one long-term UK study, compared with 96% in the general population.
Adults with CP face unique challenges as they age. Muscle and joint problems can worsen over the decades, fatigue becomes more prominent, and the physical effort of daily movement takes a greater toll. Because survival rates continue to improve, the population of adults living with CP is growing, increasing the need for healthcare providers who understand the condition beyond childhood.